Formaldehyde

Pure monomeric formaldehyde, CH2O, is colorless, pungent gas with a boiling point of -19°C, melting point at -118°C, and a molecular weight of 30.03.

Species in commercial Formaldehyde

Formaldehyde CH₂O

Methylene glycol CH₂(OH)₂

Polyoxymethylene glycol H(CH₂)_nOH (2 < n < 100)

Formaldehyde hemiformal H-O-CH₂-O-CH₃

Polyoxymethylene hemiformal H-O-(CH₂-O)_m-OCH₃ (2 < m < 80)

Trioxane (CH₂O)₃

Formaldehyde remain monomeric in nonpolar solvents below -90°C, and it polymerizes in DMSO, DMF, and THF above 90°C.

Formaldehyde decomposes rapidly into CO and H₂ above 400°C.

¹³C NMR shifts of Glycols and Hemiacetals in 37% Formaldehyde solutions.

DP Terminal Carbon Second carbon Central Carbon

1 83.8 (ppm)

2 86.9

3 87.5 90.0

4 87.7 90.4 90.8

5 90.5 91.0

6,7 90.8 91.0 91.1

Vibrational Modes of Formaldehyde